From adc95a4b5533649d6c5b620b38dab4e42117620f Mon Sep 17 00:00:00 2001
From: ThorstenB <brehmt@gmail.com>
Date: Sat, 17 Nov 2012 20:01:19 +0100
Subject: [PATCH] #600, for Curt... ;-) allow speed-up value to use fractions
 "speed-up" can now also be used for slow-motion (i.e. 0.5 / 0.25 / ...) or
 fractional speeds (3.141...). This was already working for instruments (for
 replay) before, now it's also considered by FDM simulation.

---
 src/FDM/LaRCsim/LaRCsim.cxx  | 4 ++--
 src/FDM/flight.cxx           | 9 ++++++---
 src/FDM/flight.hxx           | 1 +
 src/Main/options.cxx         | 4 ++--
 src/Network/native_ctrls.cxx | 2 +-
 5 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/FDM/LaRCsim/LaRCsim.cxx b/src/FDM/LaRCsim/LaRCsim.cxx
index 850532f34..60f54a146 100644
--- a/src/FDM/LaRCsim/LaRCsim.cxx
+++ b/src/FDM/LaRCsim/LaRCsim.cxx
@@ -269,10 +269,10 @@ void FGLaRCsim::update( double dt ) {
     }
 
     // copy control positions into the LaRCsim structure
-    Lat_control = globals->get_controls()->get_aileron() / speed_up->getIntValue();
+    Lat_control = globals->get_controls()->get_aileron() / speed_up->getDoubleValue();
     Long_control = globals->get_controls()->get_elevator();
     Long_trim = globals->get_controls()->get_elevator_trim();
-    Rudder_pedal = globals->get_controls()->get_rudder() / speed_up->getIntValue();
+    Rudder_pedal = globals->get_controls()->get_rudder() / speed_up->getDoubleValue();
 
     // IO360.cxx for the C172 thrust is broken (not sure why).  
     // So force C172 to use engine model in c172_engine.c instead of the IO360.cxx.
diff --git a/src/FDM/flight.cxx b/src/FDM/flight.cxx
index 9826d6417..c65a009a6 100644
--- a/src/FDM/flight.cxx
+++ b/src/FDM/flight.cxx
@@ -69,9 +69,11 @@ FGInterface::_calc_multiloop (double dt)
   // roundoff problems when we already have nearly accurate values.
   // Only the speedup thing must be still handled here
   int hz = fgGetInt("/sim/model-hz");
-  int multiloop = SGMiscd::roundToInt(dt*hz);
-  int speedup = fgGetInt("/sim/speed-up");
-  return multiloop * speedup;
+  double speedup = fgGetDouble("/sim/speed-up");
+  double loops = dt * hz * speedup + delta_loops;
+  int iloops = SGMiscd::roundToInt(loops);
+  delta_loops = loops-iloops; // delta_loops required for speed-ups < 1 (to do one iteration every n-th step)
+  return iloops;
 }
 
 
@@ -119,6 +121,7 @@ FGInterface::_setup ()
     climb_rate=0;
     altitude_agl=0;
     track=0;
+    delta_loops = 0.0;
 }
 
 void
diff --git a/src/FDM/flight.hxx b/src/FDM/flight.hxx
index 0cd39520b..bf1bf28bb 100644
--- a/src/FDM/flight.hxx
+++ b/src/FDM/flight.hxx
@@ -191,6 +191,7 @@ private:
     double climb_rate;                // in feet per second
     double altitude_agl;
     double track;
+    double delta_loops;
 
     simgear::TiedPropertyList _tiedProperties;
 
diff --git a/src/Main/options.cxx b/src/Main/options.cxx
index 4221df758..ae38bdc75 100644
--- a/src/Main/options.cxx
+++ b/src/Main/options.cxx
@@ -190,7 +190,7 @@ fgSetDefaults ()
     fgSetString("/sim/flight-model", "jsb");
     fgSetString("/sim/aero", "c172");
     fgSetInt("/sim/model-hz", NEW_DEFAULT_MODEL_HZ);
-    fgSetInt("/sim/speed-up", 1);
+    fgSetDouble("/sim/speed-up", 1.0);
 
 				// Rendering options
     fgSetString("/sim/rendering/fog", "nicest");
@@ -1392,7 +1392,7 @@ struct OptionDesc {
     {"aircraft-dir",                 true,  OPTION_IGNORE,   "", false, "", 0 },
     {"model-hz",                     true,  OPTION_INT,    "/sim/model-hz", false, "", 0 },
     {"max-fps",                      true,  OPTION_DOUBLE, "/sim/frame-rate-throttle-hz", false, "", 0 },
-    {"speed",                        true,  OPTION_INT,    "/sim/speed-up", false, "", 0 },
+    {"speed",                        true,  OPTION_DOUBLE, "/sim/speed-up", false, "", 0 },
     {"trim",                         false, OPTION_BOOL,   "/sim/presets/trim", true, "", 0 },
     {"notrim",                       false, OPTION_BOOL,   "/sim/presets/trim", false, "", 0 },
     {"on-ground",                    false, OPTION_BOOL,   "/sim/presets/onground", true, "", 0 },
diff --git a/src/Network/native_ctrls.cxx b/src/Network/native_ctrls.cxx
index f468b9449..19a1a482d 100644
--- a/src/Network/native_ctrls.cxx
+++ b/src/Network/native_ctrls.cxx
@@ -452,7 +452,7 @@ void FGNetCtrls2Props( FGNetCtrls *net, bool honor_freezes,
     node->setDoubleValue( "nav/frequencies/selected-mhz[0]", net->nav_1 );
     node->setDoubleValue( "nav[1]/frequencies/selected-mhz[0]", net->nav_2 );
 
-    fgSetInt( "/sim/speed-up", net->speedup );
+    fgSetDouble( "/sim/speed-up", net->speedup );
 
     if ( honor_freezes ) {
         node = fgGetNode( "/sim/freeze", true );
-- 
2.39.5